The applicability of affinity chromatography on Sepharose-IgG beads with the first component of complement as a coupling agent will be investigated. The basic adsorption and elution conditions for infectious virus-antibody complexes will be determined employing equine-arteritis virus as a model. The versatility of the technique will then be evaluated on complexes formed in vitro with IgG and IgM antibody against herpes simplex virus and on animal disease models such as LDH virus infection of mice and viral Aleutian Mink disease.